Class 11 Chemistry Redox Reactions Types of Redox reactions

Types of Redox reactions

  1. Combination reaction: When two or more reactants react to form single product.

i.e   a + b --> ab (in this single product is formed).

For the reaction to be Redox, both the elements should be in elemental form.

For example: All combustion reactions are Redox reactions.

C0        + O2 -->   CO2

Carbon  Oxygen  Carbondioxide

  1. Decomposition reaction: It is the type of reaction, in which a reactant breaks up into its constituents either by heating, passing current or in presence of light.


  1. Displacement reaction: It is the reaction between element and a compound. In This more reactive element displaces less reactive from its compound.

CuSO4            + Zn         --> ZnSO4 + Cu

Copper Sulphate  Zinc                Zinc Sulphate Copper

Displacement reactions fit into two categories: metal displacement and non metal displacement.

Metal displacement: a metal in a compound can be displaced by another metal in the uncombined state .Metal displacement reactions find many applications in metallurgy. Few examples are:


Non-metal displacement: The non metal displacement involves mainly displacement of hydrogen and a rarely occurring reaction involving oxygen displacement .For example:


Non metal non-metal displacement: in this non metal gets displaced by non metal according to reactivities .For example if we consider fluorine and chlorine so, it is but obvious that fluorine can replace chlorine as it is more reactive.


  1. Disproportionate reaction: A reaction in which the same species is simultaneously reduced and oxidized .One of the reacting species in this reaction is always an element, that can exist in at least three oxidation states .The element in the form of reacting species is in the intermediate oxidation state .In this higher and lower both oxidation states of the element are formed.
  2. For Example:- 

      H2O2         -->   H2O    +  H2

Hydrogen Peroxide  Water Oxygen Gas

In above example, the oxidation number of Oxygen which is -1 in peroxide increases to zero in O2 and decreases to -2 in water.

There are two types of Redox reactions

  • Direct Redox reaction
  • Indirect Redox reaction

Direct Redox reaction: In which oxidation and reduction both occur in same beaker. In this electron so produced does not travel to large distance.

For example: A beaker containing Zinc rod dipped in Copper sulphate solution in this the following reaction occur:

Zn    +    CuSO4 -->       ZnSO4 + Cu

Zinc   CopperSulphate  Zinc Sulphate  Copper

In this zinc being more reactive displaces copper from copper sulphate and forms zinc sulphate and copper.

Indirect Redox reactions: In it oxidation and reduction occur in different beakers. The electron so produced has to travel a certain distance that leads to generation of current.

Example: Daniel cell: A cell containing Zn-Cu couple that we are going to study in detail now as given below but before that let us make you familiar with the general term used in redox reaction that is Redox couple.

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